150 Prof. J. J. Thomson on the 



to show, explain the various electrical processes, — such as the 

 passage of electricity through metals, liquids, or gases, the 

 production of a current, magnetic force, the induction of 

 currents, and so on, — as arising from the contraction or elonga- 

 tion of such tubes and their motion through the electric 

 field. 



We might, as we shall see, have taken the tubes of mag- 

 netic force as the quantity by which to express all the changes 

 in the electric field ; the reason I have chosen the tubes of 

 electrostatic induction is that the intimate relation between 

 electrical charges and atomic structure seems to point to the 

 conclusion that it is the tubes of electrostatic induction which 

 are most directly involved in the many cases in which 

 electrical charges are accompanied by chemical ones. 



We may regard the method from one point of view as 

 being a kind of molecular theory of electricity, the properties 

 of the electric field being explained as the effects produced 

 by the motion of multitudes of tubes of electrostatic induc- 

 tion ; just as in the molecular theory of gases the properties 

 of the gas are explained as the result of the motion of its 

 molecules. 



As the principal reason for expressing the effects in terms 

 of the tubes of electrostatic induction is the close connexion 

 between electrical and chemical properties, we shall begin by 

 considering at some length the connexion between these 

 tubes of electrostatic induction and the atoms of bodies. 



We assume, then, that the electric field is full of tubes of 

 electrostatic induction, that these are all of the same strength, 

 and that this strength is such that when a tube falls on a 

 conductor it corresponds to a negative charge on the con- 

 ductor equal in amount to the charge which in electrolysis 

 we find associated with an atom of a univalent element. 



These tubes must either form closed circuits or they must 

 end on atoms, any unclosed tube being a tube connecting two 

 atoms. In this respect the tubes resemble lines of vorticity in 

 hydrodynamics, as these lines must either be closed, or have 

 their extremities on a boundary of the fluid. 



We may suppose that associated with these tubes of electro- 

 static induction there is a distribution of velocity, both in 

 themselves and in the surrounding aether, and that the energy 

 due to this motion of the medium constitutes the energy 

 which is distributed throughout the electric field. In addi- 

 tion to there being this energy in the medium, the incidence 

 of a tube of force on an atom may modify the interual motion 

 of the atom, and thus alter its energy, so that, in addition to 

 the energy in the field, there may be a certain amount of 



